PORTLAND — Voters are likely to be asked in November if they want to elect a mayor using ranked-choice voting.

The Charter Commission endorsed ranked-choice voting in a Jan. 28 meeting. The voting method, also known as instant run-off voting, allows voters to rank candidates in order of preference and is intended to eliminate pluralities. A candidate would have to receive 50 percent of the vote in order to take office.

“The feeling is, if we are going to have this new elected mayor position, we could end up with five or six candidates,” said Commissioner Ben Chipman. “We don’t want someone with 20 percent of the vote winning.”

In November, the commission endorsed a draft change to the City Charter that would make the mayoral position in Portland popularly elected. The mayor would have more power over policy, budgetary issues and city administration. Currently, a city councilor is chosen by the rest of the council to serve as mayor for a one-year term and the position is largely ceremonial.

The commission voted 9-1 in favor of ranked-choice voting at its meeting last month. Commissioner Richard Ranaghan was opposed, and commissioners Naomi Mermin and Nathan Smith were absent. The commission did not endorse using ranked-choice voting for City Council or School Board elections.

In ranked-choice voting, if no candidate gets at least 50 percent of the first-choice vote, the second-choice votes are tallied and added to the candidates’ totals. This continues through subsequent preferences until one candidate has at least 50 percent.

Chipman, a supporter of ranked-choice voting, said it is unclear how much it would cost to implement the change. The city may have to get new electronic voting machines, which would cost $105,000. Or it could purchase software that would allow existing current machines to process ranked-choice ballots.

There is also a cost component associated with educating voters. Burlington, Vt., switched to ranked choice in 2005 and spent about $20,000, according to Charter Commission minutes from Jan. 14.

Chipman said the city would also have to figure out how to make its voting machines compatible with local and state ballots.

“Ranked-choice voting has never been used in Maine,” he said. “There are some unknowns – staffing constraints, timing, costs.”

The commission has asked the city clerk to research the most cost-effective way to implement the change.

The Charter Commission has been working since last summer to review the charter and come up with suggested changes. Those proposed changes will eventually go to voters for approval.